Study of ion-to-electron temperature ratio at the edge of Wendelstein 7-X using a fast swept ball-pen probe

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F25%3A00647282" target="_blank" >RIV/61389021:_____/25:00647282 - isvavai.cz</a>

Výsledek na webu

<a href="https://iopscience.iop.org/article/10.1088/1361-6587/ae1b6b" target="_blank" >https://iopscience.iop.org/article/10.1088/1361-6587/ae1b6b</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1361-6587/ae1b6b" target="_blank" >10.1088/1361-6587/ae1b6b</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Study of ion-to-electron temperature ratio at the edge of Wendelstein 7-X using a fast swept ball-pen probe

Popis výsledku v původním jazyce

In the Wendelstein 7-X (W7-X) stellarator, a ball-pen probe (BPP) has been routinely employed to measure Ti in the island scrape-off layer (SOL) across large parts of the recent 2024/2025 campaigns. The high temporal resolution of 25 mu s allows us to resolve Ti fluctuations, their probability density functions, and modulation via low-frequency magnetohydrodynamics (MHD) modes. We present a unique comparison of the ion temperature measured using BPP with a more conventional retarding field analyzer (RFA). A good agreement between the two diagnostics is observed, when fast Ti measurements are reduced to the same temporal resolution (5 ms) using 'RFA-like' averaging. Using an RFA-like interpretation of the fast BPP data, we find a linear decrease in SOL Ti and Te with line-integrated density. The SOL ion-to-electron temperature ratio tau i,e ranges between tau i,e= 1 and 3 with smaller tau i,e values observed for higher densities (collisionalities) and at positions close to the LCFS. The upstream BPP Ti measurements are compared to the average C2+ Ti obtained by coherence imaging spectroscopy (CIS), in the divertor region, magnetically mapped to the BPP. The downstream Ti measured by CIS is about half the upstream Ti and exhibits a similar inverse scaling with line-integrated density. Finally, we benchmark the experimentally obtained SOL Ti and Te against the EMC3-Eirene modeling and find good agreement for high density plasmas, but significantly diverging results for low density plasmas.

Název v anglickém jazyce

Study of ion-to-electron temperature ratio at the edge of Wendelstein 7-X using a fast swept ball-pen probe

Popis výsledku anglicky

In the Wendelstein 7-X (W7-X) stellarator, a ball-pen probe (BPP) has been routinely employed to measure Ti in the island scrape-off layer (SOL) across large parts of the recent 2024/2025 campaigns. The high temporal resolution of 25 mu s allows us to resolve Ti fluctuations, their probability density functions, and modulation via low-frequency magnetohydrodynamics (MHD) modes. We present a unique comparison of the ion temperature measured using BPP with a more conventional retarding field analyzer (RFA). A good agreement between the two diagnostics is observed, when fast Ti measurements are reduced to the same temporal resolution (5 ms) using 'RFA-like' averaging. Using an RFA-like interpretation of the fast BPP data, we find a linear decrease in SOL Ti and Te with line-integrated density. The SOL ion-to-electron temperature ratio tau i,e ranges between tau i,e= 1 and 3 with smaller tau i,e values observed for higher densities (collisionalities) and at positions close to the LCFS. The upstream BPP Ti measurements are compared to the average C2+ Ti obtained by coherence imaging spectroscopy (CIS), in the divertor region, magnetically mapped to the BPP. The downstream Ti measured by CIS is about half the upstream Ti and exhibits a similar inverse scaling with line-integrated density. Finally, we benchmark the experimentally obtained SOL Ti and Te against the EMC3-Eirene modeling and find good agreement for high density plasmas, but significantly diverging results for low density plasmas.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

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OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Plasma Physics and Controlled Fusion

ISSN

0741-3335

e-ISSN

1361-6587

Svazek periodika

67

Číslo periodika v rámci svazku

11

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

14

Strana od-do

115029

Kód UT WoS článku

001620224700001

EID výsledku v databázi Scopus

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